Increased nut consumption has been associated with a reduced risk of major chronic diseases, including cardiovascular disease and type 2 diabetes.
The researchers examined the association between nut consumption and subsequent total and cause-specific mortality among 76,464 women in the Nurses' Health Study (1980–2010) and 42,498 men in the Health Professionals Follow-up Study (1986–2010). Participants with a history of cancer, heart disease, or stroke were excluded. Nut consumption was assessed with the use of validated food-frequency questionnaires at baseline and updated every 2–4 years.
In the 1980 and 1984 dietary questionnaires, the researchers asked the participants how often they had consumed a serving of nuts (serving size 28 g or 1 oz) during the preceding year: never or almost never, one to three times a month, once a week, two to four times a week, five or six times a week, once a day, two or three times a day, four to six times a day, or more than six times a day. In the subsequent dietary questionnaires, the question regarding nuts was split into two items: peanuts and other nuts. Total nut consumption was defined as the intake of peanuts and other nuts.
During the follow-up period, 16,200 women and 11,229 men died. Nut consumption was inversely associated with total mortality among both women and men, after adjustment for other known or suspected risk factors. People who ate nuts seven or more times per week had a 20% lower death rate when compared with people who did not eat nuts. Significant inverse associations were also observed between nut consumption and deaths due to cancer, heart disease, and respiratory disease. The researchers noted that there may be a concern that frequent nut consumption can result in weight gain. However, in these two cohorts, increased nut intake was associated with less weight gain.
The researchers concluded that the "analysis of samples from these two prospective cohort studies showed significant inverse associations of nut consumption with total and cause-specific mortality. Nonetheless, epidemiologic observations establish associations, not causality, and not all findings from observational studies have been confirmed in controlled, randomized clinical trials."